It has been known for a long time that lubrication between railroad wheel flanges and the gage sides of the rails reduces wear of the rail and the wheel flanges on curves. Recent field tests have indicated that significant reductions of train resistance and savings of fuel consumption can be achieved when the gage sides of the rail are lubricated for both tangent and curved track. These fuel savings have been found to be between 5 and 30 percent. Other benefits that result from such lubrication are reductions in wheel rail noise and in the tendency of cars to hunt.
There are currently two methods of applying such lubrication. These are wayside lubrication on curves and onboard flange lubrication. The wayside method has been largely used in the U.S. The wayside lubricators are long bars with lubricant injection along their length from wayside lubricant tanks, powered by a pump. The lubricant is carried by the wheel flanges and rubbed on the gage side of the rail for several hundred to several thousand feet. The amount of lubricant injected through the bars is adjusted mechanically depending on the sharpness and length of the curve. There are several problems because of which these lubrication systems are not the most suitable for application to curved and tangent track as needed today. These lubricators require regular staff to service and maintain the lubrication in remote areas where the track is laid out. They have frequent mechanical failures and apply lubricant only for a specified short distance. They apply too much lubricant near the lubricator resulting in several associated problems and too little lubricant away from the lubricators. Such lubricators are not suitable for application of lubricant to tangent track because too many of them will be needed for the whole track.
On-board flange lubricators consist of on-board lubrication kept in a locomotive or other powered car and applied through a nozzle or a similar device to wheel flanges of the locomotive. The application of the lubricant is triggered by the approach of the locomotive to a curve. These lubricators have a constant rate of lubrication and do not transfer lubricant from wheel to rail on tangent track much of the time because the flange is not rubbing against the gage side of the rail much of the time. It has been estimated that nearly 95% of the lubricant is thrown around and only 5% is used in the flange contact. While these lubricators are used by many railroads, they are not ideally suited for tangent track.
None of the lubricators available to date do the complete job demanded for both tangent and curved track. A very important aspect in which they are all quite deficient is that all of them attempt to reduce only the friction coefficient between the wheel flange and the rail. None of them attack at the root of the wear energy loss problem, which is the large force that is produced between the flange and the rail. In order to reduce wheel/rail wear and energy loss, it is necessary to reduce both the friction coefficient as well as the force with which the flange rubs on the rail.
As discussed earlier, rail gage and wheel flange lubrication has been found to be beneficial in terms of reduction of wheel/rail wear as well as reduction of fuel consumption when such lubrication is applied on curved as well as tangent track. There are a number of problems, however, that need to be resolved for proper lubrication of the wheel and rail. None of the systems available to date apply the lubricant correctly and effectively on tangent track. None of them control and change the amount of lubricant with the tonnage being hauled, the angle of attack of the wheel on the rail and the environmental conditions such as temperature. All lubrication systems to date are aimed at reducing the friction coefficient of the flange and the rail. None of them are aimed at reducing the force with which the flange rubs the rail. To get around the above problems, most lubricators end up applying too much lubricant. This results in environmental pollution as well as loss of adhesion for the locomotives and growth of undetected internal fatigue cracks in the rail which can be disastrous.
A difficulty in achieving some of the above-stated considerations is that there are conflicting requirements between good performance of the locomotive wheels and good performance of the freight car wheels. The locomotive wheels require a high level of adhesion or friction and therefore need little or no lubrication, and the car wheels require adequate lubrication to reduce the wheel/rail contact friction.